What Is Permit2?
Permit2 is a Uniswap-designed contract that lets you grant token allowances with a signature instead of a separate on-chain approve transaction. You sign a message: this spender, this amount, this deadline. The first time, you still approve the Permit2 contract itself. After that, many apps can pull through Permit2 without another approve, which saves gas and clicks.
How It Actually Works
- Classic ERC-20 approve is a transaction. Permit (EIP-2612) is a per-token signed allowance. Permit2 is a shared hub so tokens that never implemented permit can still do signature allowances.
- Wallets that understand Permit2 can show "Uniswap is asking to move 100 USDC until Friday." Wallets that do not just show a mystery signature.
- Revoking still matters. You can revoke the Permit2 allowance on the token, or revoke specific permits. Revoke.cash knows this surface.
Risks and Common Mistakes
- Signing a permit on a fake site. No transaction pop-up does not mean no permission. Drainers love "gasless" signatures.
- Unlimited Permit2 approval to the hub, then blindly signing every follow-up. The hub is only as safe as what you permit through it.
- Using a wallet that cannot decode the permit. If you cannot read the spender and the amount, do not sign. Rabby is built for this moment.
When It Matters
Every modern Uniswap-style swap prompt, and any "sign to approve, no gas" flow. Convenient is not the same as harmless. The Security page still starts with: read before you sign.
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